Paper machine dryer drive mechanism



July 8, 1958 L. HORNBOSTEL PAPER MACHINE DRYER DRIVE MECHANISM Filed Sept. 30. 1955 ii ERIE? [Love HoRA/BosTEL passed through the dryers.

United States PatenrO PAPER MACHINE DRYER DRIVEMECHANEM Lloyd Hornbostel, Beloit, Wis., assignor to Beloit Iron The presentinvention-relates to the operation of the dryers in a paper machine, and more particularly, to a drive mechanism for a paper machine dryer. I

As is well known, in a paper machine the paper web is ordinarily removed from a suitable forming surface, passed through presses to dewater the web, and then The dryers are ordinarily divided up into sections, the first section being referred to as the wet end, and the dry end may involve one or more sections. The dryer (or each dryer section) coniprises a plurality'of dryer rolls which are hollow drums having steam inlet and condensate removal lines connected thereto and these rolls are ordinarily aligned in tiers, with each roll in the top tier being positioned inter- .mediate a pair of rolls inthe bottom tier, so that the web may pass beneath a bottom roll then upwardly over an upper roll, and then downwardly beneath the next bottom roll. The rolls in each tier and the tiers themselves' are closely spaced andbreaks in the paper web traveling through the dryer present quite a-problem to the industry in production loss, as well as difficulties in 35 rethreading the web through-the dryer. Heretofore, the reasons for many breaks in the web passing through the dryer were not understood.

The instant invention is based in part on a discovery of one of the causes for such breaks in the web passing through the dryer and in part on a discovery of an imsame for diflerent grades andweights. Also, the place in the dryer section where the dimensional changes take place will vary with sheet weight and grade.

In ordinary practice the dryer drums are all driven at the same speed so that any growth or shrinkage of the web at one place or another in the dryer may result in the web becoming either too tight or too slack. The instant invention, however, contemplates driving such rolls or drums at different speeds by virtue of a differential gearing arrangement which will be described in detail hereinafter. The differential drive is inherently very accurate so that it permits varying only a very small percentage of the speeds of the dryer drums, or permits a speed differential. therebetween that is only a very small percentage of the driven speed of the drums.

It is therefore an important object of the instant invention to provide an improved drive mechanism for a paper machine dryer.

It is a further object of the instant invention to provide an improved drive mechanism for driving adjacent rolls in a paper machine dryer at different speeds to effect proper tensioning'of the web traveling therebetween, so

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as to avoid a tendency for the web to wrinkle or break at such location.

Other and further objects, features and advantages of "the present invention will become apparent to those skilled inthe art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings: Figure l is essentially a diagrammatic top plan view of a paper machine drive mechanism embodying the instant invention;

Figure 2 is essentially a diagrammatic elevational view taken substantially along the line II- H of Figure 1; and Figure 3 is a top plan view of a differential gearing assembly and associated gears employed in the drive mechanism of the instant invention. Asshown on the drawings: I i In Figure l, a paper machine, indicated generally by the reference numeral HP, is shown partially with a couchroll ll atone end, first, secondand third presses 12; 13 and 14 next, dryer rolls 15, 16, 17, 18, 19 and -20 in the top tier of the dryer (with primed reference numerals indicating corresponding dryer rolls in the bottom-tier of the dryer) and finally a calender stack 21 at the other end of themachine 10. The couch roll 11, --first,-second and third presses 12, 13 and 1 5, and calender 'stack21 are'each driven by separate cone pulley and bevel =gearing assemblies its, 120, 13a, etc., each connected to awari'able speed line shaft 22 driven by a prime mover or main drive motor 23 connected thereto through a siiitablebelt and pulley arrangement 23a, as indicated.

i In thedryer, rolls 15, 16, 17, 18, 19 and 2t) define the y top tier; and rolls 15, 16, 17', i8, 19, 2t) define the bottom tier; with the top tier rolls being positioned inter *mediatethe bottom tier rolls. Ordinarily, drive mecha- -ni'srn for thedryer would afford a connection between the rolls 16 and16-of the first section and the roll 17 of the second section so that all of these rolls would be driven atsubstantially the same speed.

in the instantinvention, however, as best'shown in Figure 2, a driven gear 24 drives a main gear 16'a directly connected tothe roll 16', and the driven gear 24 also drives a' second gearZS whiclrin turn drives the main-"gear itia' directly attached to the upper roll 16. r in this 111ani1er3therolls 16 and 16" are driven at substantially the same rate of speed. As here used, rate of speedrneans srn'face speed or peripheral speed of the ten, but it will be appreciated that in most cases all of the dryer rollsare of"substantially the same size. A "second driven gearz fi separate and apart from the gears 24: and 25-drives the maingear 17a of the lower roll 1'7; 'but the instant drive mechanism is arranged, as will be explained, so that the roll 17' is driven at a slightly diiferent speedthan the rolls l6 and 16 thus avoiding slack or wrinkling (whichever itmay be) of the web rea'cHWR betweenthe sections and between the last rollifiof the first section and the first roll 17' of the second "section. '"As' is customary in dryers, an upper felt 27 mountedon guide rolls 28, 29 and 3b is wrapped over theweb Win' its" travel over each of the top rolls 15; 16, etc. and abottom felt 31 on guide rolls 32, 33, 34, 'etc. is wrapped over the web W as it travels on the bottom side of each of the bottom rolls 15, 16, etc.

"Referring now to Figure 3 which shows certain details of the 'drive mechanism within a housing 40 (indicated in dotted lines in Figure 3) it will be noted that T the driven gears-24 and 26 are shown only partially. 'in drivingthe dryerroll 17, through the driven gear '26, itwill be noted that thed'esired speed is imparted 0 to a' secondarydine shaft 41 (through asuitable cone pulley and" belt arrangement directly connected to the -rn'ain lineshaft 22,asiiidicated at 42 in Figure 1). The

secondary line shaft drives, through bevel gears 42a, 42b, a main drive shaft 43 passing through the housing 40 and carried on bearings indicated diagrammatically at 44 and 45. The main drive shaft 43 has a gear 46 corotatably mounted thereon for driving the gear 26 V which in turn drives the dryer roll 17' at the speed desired. This affords a direct mechanical connection between the secondary line shaft 41 and the dryer roll 17' to drive the roll 17 at a fixed speed. The main drive shaft 43 has a second gear 47 corotatably mounted thereon within the housing it and the gear 4-7 is meshed with a gear 4-5 carried. on a second shaft 49 to drive the shaft 4%. The shaft 49, in turn, drives a gear 50 corotatably mounted thereon. For the sake of simplicity, bearings within the housing 4% have been omitted. The gear St) is meshed with and drives a gear 51 (shown in section) corotatably carried on a sleeve 52 freely rotatable on a shaft 53. The sleeve 52 also carries a (beveled) pinion 54- corotatably mounted thereon. A separate shaft 55 carries an opposed (beveled) pinion 56 corotatably mounted thereon. Opposed (beveled) pinions 57 and 53 rotatably carried on a frame or rack 59 are each meshed with both of the opposed pinions 54 and 56. The frame 59 forms with the shaft 53 a T- shaped arrangement whereby the pinions 57 and 58 are carried at the extremities of the arms of the T and are rotatable about the stem 53 of the T.

As is well understood in the operation of differential gear assemblies, such as the differential gearing assembly 54, 56, 59 (plus 57 and 58), if the frame 59 is held against rotation (i. e., if torque is applied to the frame .59 to hold the same against rotation) and the pinions 54 and 56 are of the same size the speed of rotation of the driving pinion 54 will be the same as the speed of the rotation of the driven pinion 56. If, however, the frame 59 is rotated in one direction or the other the resulting speed of the pinion 56 will be correspondingly greater or less than the speed of the driving pinion 54. The differential gearing assembly here shown comprises three rotary elements 54, 56 and 59. The rotary gear elements 54, 56 and 59 include a first element in the form of the pinion 54 in driven connection with the main drive shaft 43, a second rotary gear element in the form of the pinion 56 in driving connection with a roll 16' (as will be explained hereinafter) and a control rotary gear element in the form of the frame 59 carrying the pinions 57 and 58. It will be appreciated that differential gearing assemblies will permit the use of a gear instead of the frame as a control member, and vice versa; but in the particular embodiment here shown the frame element 59 rotatably supporting pinions 57 and 58 is the control element and the pinions 54 and 56 are each gears respectively connected to the driving and the driven elements. The pinion 56 drives the shaft 55 which in turn drives a gear 60 corotatably mounted thereon. The gear 60 meshes with and drives a gear 61 on a driven shaft 62, carried on a bearing 63, and corotatably mounting a gear 64 which meshes with and drives the second driving gear 24. The second driving gear 24, as shown in Figure 2, drives the roll 16 directly and the roll 16 indirectly through the gear 25.

Means are provided for applying variable speed (i. e. a form of torque) to the control element or frame 59 through the shaft 53 (via the gears 65 and 66), in the form of a variable speed ratio element or unit 67, defined by cone pulleys 67a (on the shaft 43) and 6712 (connected to the gear 66 (interconnected by an adjustable belt 670). The speed differential in R. P. M. between the gears 54 and 56 will be equal to the output R. P. M. of the variable speed ratio element 67. As here shown the rolls 16 and 16 are driven at the same speed by the same drive shaft 62 through the gearing indicated. The control element 59 is thus operated to drive the rolls 16 and 16 at a slightly slower speed than the roll 17' is 4 driven by the main drive shaft 43. This results in a tensioning of the web reach WR between the rolls 16 and 17' and it has been found to reduce materially the number of breaks in the web in the dryer.

Although the elastic properties of the web W will permit certain variations in the tension applied thereto without causing rupture of the web merely by the application of excessive tension thereto, depending upon the weight and type of paper, the speeds in R. P. M. of the two rolls 16 and 17' may be fixed so as to provide differential which will impart a relatively small but appreciable amount of tension to the web at the web reach WR and prevent slapping of the web at this point. No further adjustment would thus be necessary since the differential gearing assembly 54, 56 and 59 would automatically compensate for changes in the speed of the main line shaft 22 so as to maintain the desired speed differential between the rolls 16 and 17. However, it is also advantageous to employ a low power unit 67 to operate the control element 59, so that the torque applied to the roll 16 to rotate this roll at a fixed speed would yield to the torque which the roll 17 might apply to the roll 16 through the paper reach WR. In other words, once the tension on the paper reach WR reached a given tension, and thus applied a given torque to the roll 16, this roll would be governed thereby and the effect of such torque would be to overcome the torque applied in the operation of the differential gearing assembly.

It will also be appreciated that the main drive shaft 43 and the driven shaft 62 might be reversed in the practice of the instant invention, so that the main drive shaft would drive the slower of the two rolls, i. e., the roll 16 and the driven shaft 62 would drive the faster of the two rolls, i. e., the roll 17 and the differential gearing assembly 54, 56 and 59 would be used to increase the speed rather than decrease the speed. In still another arrangement the unit 67 may be operated to drive the roll 16' faster than the roll 17 (to relieve excessive tension in the web therebetween).

It might be further noted that only a slight speed differential (relative to the speed of rotation of the rolls) is required to obtain the proper tension in the web, and the power applied or absorbed by the control element in the differential gearing arrangement of this invention bears substantially the same ratio to the total power required to drive the speed-controlled roll as the speed differential bears to the speed of the speed-controlled roll, neglecting friction in the gearing assembly. Accordingly, the controlling element, in this case the unit 67, may be very small in size and readily controlled. If a separate speed-controlled prime mover were used forone of the rolls, such would have to be large in size and difficult to control. A

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

I claim as my invention:

1. In a paper machine dryer, a first dryer roll, a second dryer roll adjacent thereto and cooperating with said first roll to support a reach of traveling paper web therebetween, a main drive imparting a predetermined speed to said first roll to rotate the same, a first rotary gear element in driven connection with said main drive, a second rotary gear element in driving connection with said second roll, and a control rotary gear element arranged with said first and second elements to define a differential gearing assembly, and driven with a variable speed ratio element which in turn is driven from said first rotary gear element, said variable speed ratio element provides means for applying a speed variation 1 ond dryer roll, said second dryer roll being the last in a dryer section and said first roll being the first in the next dryer section with a reach of traveling web extending therebetween, a main drive imparting a predetermined torque to said first roll to rotate the same at a given speed, a first rotary gear element in driven connection with said main drive, a second rotary gear element in driving connection with said second roll, a control rotary gear element arranged with said first and second elements to define a differential gearing assembly, and means actuated by said main drive applying variable speed to said control element to impart, via said differential gearing assembly, to said second roll a speed increase from that of said first roll to tension the web reach extending therebetween.

3. in a paper machine dryer, a first dryer roll, a second dryer roll with a reach of traveling web extending therebetween, a main drive imparting a predetermined speed to said first roll, a differential gearing assembly having three rotary gear elements which are a frame element rotatably supporting a pinion and two gears meshed with the pinion, one of said gears being in driven connection with said main drive, the other of said gears being in driving connection with said second roll, and means actuated by said main drive applying torque to the third of said elements to impart, via said differential gearing assembly, to said second roll a speed greater than the speed of the first roll to tension the web therebetween.

4. In a paper machine dryer, a first dryer roll, a second dryer roll adjacent thereto and cooperating with said first dryer roll to support a reach of traveling paper web therebetween, a main drive imparting a predetermined speed to said first roll to rotate the same, a first rotary gear element in driven connection with said main drive, a second rotary gear element in driving connection with said second roll, a control rotary gear element arranged with said first and second elements to define a differential gearing assembly, a first cone pulley corotatably mounted with said first rotary gear element, a second cone pulley corotatably mounted with said control rotary element, and a belt interconnecting said pulleys and arranged therewith to define a variable speed ratio element actuated by said first rotary gear element and applying speed variation to said control element to create a speed differential between said rolls.

5. In a paper machine dryer, a first roll, a second roll adjacent thereto and cooperating therewith to pass a paper web therebetween, a main drive imparting a pre determined speed to said first roll to rotate the same, a first rotary gear element in driven connection with said main drive, a second rotary gear element in driving connection with said second roll, a control rotary gear element arranged with said first and second elements to define a difierential gearing assembly, first means providing a variable effective diameter co-rotatably mounted with said first rotary gear element, second means providing a variable efiective diameter co-rotatably mounted with said second rotary gear element, and endless flexible means interconnecting said first and second means and arranged therewith to define a variable speed ratio element actuated by said first rotary gear element and applying speed variation to said control element to create a speed difierential between said rolls.

References Cited in the file of this patent UNITED STATES PATENTS 

